chore(project): close STORY-013 (learner profile schema done)

[khoks]

Summary

• Marks STORY-013 done in the tracker. Schema landed in PR #11 (commit 69f5938).
• Updates BOARD.md: STORY-013 moves from In Progress → Recently Done. EPIC-005 has its first feature Story closed.
• No code changes.

Test plan

• Markdown-only — no code, no CI checks needed.
• Tracker frontmatter sets status: done.
• Activity log includes the merge reference.

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